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KVM: x86/xen: add support for 32-bit guests in SCHEDOP_poll 

This patch introduces compat version of struct sched_poll for
SCHEDOP_poll sub-operation of sched_op hypercall, reads correct amount
of data (16 bytes in 32-bit case, 24 bytes otherwise) by using new
compat_sched_poll struct, copies it to sched_poll properly, and lets
rest of the code run as is.

Signed-off-by: Metin Kaya <metikaya@amazon.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
This commit is contained in:
Metin Kaya 2022-03-21 11:05:32 +00:00 committed by David Woodhouse
parent df0bb47baa
commit 214b0a88c4
2 changed files with 36 additions and 4 deletions
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33
arch/x86/kvm/xen.c
View File

@ -1201,20 +1201,45 @@ static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode,
evtchn_port_t port, *ports;
gpa_t gpa;
if (!longmode || !lapic_in_kernel(vcpu) ||
if (!lapic_in_kernel(vcpu) ||
!(vcpu->kvm->arch.xen_hvm_config.flags & KVM_XEN_HVM_CONFIG_EVTCHN_SEND))
return false;
idx = srcu_read_lock(&vcpu->kvm->srcu);
gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
if (!gpa || kvm_vcpu_read_guest(vcpu, gpa, &sched_poll,
sizeof(sched_poll))) {
if (!gpa) {
*r = -EFAULT;
return true;
}
if (IS_ENABLED(CONFIG_64BIT) && !longmode) {
struct compat_sched_poll sp32;
/* Sanity check that the compat struct definition is correct */
BUILD_BUG_ON(sizeof(sp32) != 16);
if (kvm_vcpu_read_guest(vcpu, gpa, &sp32, sizeof(sp32))) {
*r = -EFAULT;
return true;
}
/*
* This is a 32-bit pointer to an array of evtchn_port_t which
* are uint32_t, so once it's converted no further compat
* handling is needed.
*/
sched_poll.ports = (void *)(unsigned long)(sp32.ports);
sched_poll.nr_ports = sp32.nr_ports;
sched_poll.timeout = sp32.timeout;
} else {
if (kvm_vcpu_read_guest(vcpu, gpa, &sched_poll,
sizeof(sched_poll))) {
*r = -EFAULT;
return true;
}
}
if (unlikely(sched_poll.nr_ports > 1)) {
/* Xen (unofficially) limits number of pollers to 128 */
if (sched_poll.nr_ports > 128) {

7
arch/x86/kvm/xen.h
View File

@ -207,4 +207,11 @@ struct compat_vcpu_runstate_info {
uint64_t time[4];
} __attribute__((packed));
struct compat_sched_poll {
/* This is actually a guest virtual address which points to ports. */
uint32_t ports;
unsigned int nr_ports;
uint64_t timeout;
};
#endif /* __ARCH_X86_KVM_XEN_H__ */